KR20120075416A - A reaming tool as well as a head and a cutting insert therefor - Google Patents

Abstract

PURPOSE: A head and a cutting insert for a reaming tool and the reaming tool are provided to use four cutting blades by forming a reaming insert into diamond shape. CONSTITUTION: A reaming tool comprises a cutting insert(3) and a seat(17). The cutting insert comprises four clearance surfaces(30) and diamond-shaped sections in the symmetrical plane. The clearance surfaces are contacted with each other in facing corners(31). Two cutting blades(33) are formed along each chip surface(29) and used with a chip surface alternatively by an indexing of the cutting insert. The seat comprises a radial supporting surface(18), a tangential supporting surface(19), and an inclined surface(22). The inclined surface is formed at an obtuse angle based on the ground.

Description

A REAMING TOOL AS WELL AS A HEAD AND A CUTTING INSERT THEREFOR}

In a first aspect, the invention is a reaming tool of the type comprising a head having a basic shape of drive rod and rotationally symmetrical and to which at least one removable cutting insert is mounted, the head having a front and rear end surface, An envelope surface concentric with the central axis, and a sheet having a countersink upwardly at the envelope surface, the sheet comprising three support surfaces, one of which is radially supported Face and the other is the tangential support surface, the cutting insert has the shape of a mirror-symmetric polygon comprising six confinement surfaces, of which two mutually parallel opposing surfaces are equidistantly separated from the central symmetry plane Forming a surface, the chip surface serving as a clearance surface, via alternately available identical cutting edges And connected to, the cutting insert is directed to the reaming tool is held fixed to the sheet by a clamping member.

In a further aspect, the invention also relates to such a tool head and a cutting insert.

Tools of the type related to the above are used to ream holes in metal workpieces by chip removal or cutting machining, with the aim of giving the holes a smooth, cylindrical surface with a precisely determined diameter. Advantageously the product which can be machined by the tool is a tube blank, and the inside of the tube blank has to be accurate in dimension and for a high surface smoothness for several reasons. In practice, the only common way to machine a tube blank is so-called pull boring. The tool is then connected with one end of the drawbar, the drawbar having an outer diameter smaller than the inner diameter of the tube blank, and in a first step, through the tube blank, so that the tool is at its free end, for example It can be applied via threaded joints, and then the reaming operation is done by a combination of linear and rotary motions between the tool and the tube blank. Typically, the tool is conveyed in the longitudinal direction as the tube blank is rotated and pulled through the interior of the tube blank without rotation. By this relative movement, the cutting insert detachably installed in the tool head removes the chip from the hole wall while creating a cylindrical surface with good dimensional accuracy and high surface smoothness in a characteristic manner of cutting machining.

The prismatic cutting inserts used in known reaming tools of the type related to the above have two opposing chip surfaces; An upper side and a lower side longer than the upper side; Two opposing end faces; And two clearance surfaces extending from the upper side toward the end surface and then inclined downward toward the end surface. Therefore, there is only one cutting edge available for the same tool along each chip surface, ie at the transition towards the individual clearance surface. This means that the cutting insert comprises only two alternatingly available cutting edges in total. Because of the volume of the cutting insert, the amount of expensive material (carbide) will be unbalanced relative to the number of cutting edges available, and the user's working profit per cutting insert will not be very good. Thus, known cutting inserts are invertible, but not indexable to allow the use of other edges of the cutting insert as cutting edges. Another disadvantage of known cutting inserts is that when the accessory seat is subjected to reverse interaction of force, the cutting insert tends to be displaced or even loose from the accessory sheet. Thus, current reaming methods are usually reliable and function properly, but sometimes breakdowns occur, the machining operation must be interrupted, and the tool is retracted out of the hole. Examples of failures include one or more cutting inserts being damaged or loosened from the tool head, or the drive fixture is stopped. In connection with such a retraction, the intact cutting inserts of the tool head can be caught against the inside of the tube blank, and the cutting inserts are subjected to the opposite interaction of force, which tends to cause the cutting inserts to deviate from the accessory sheet. The cutting insert is kept away from the tangential support surface, in particular the axial support surface, instead of being automatically pressed against all the support surfaces of the seat by the cutting force during operation. However, if a screw is used as the clamping member, the screw is less likely to withstand reversed forces. The characteristic of the screw is that it has good tensile strength but very poor flexural strength. Thus, if the tool has a medium diameter and the cutting insert and the screw are relatively small, it is easy to break the screw in the sudden opposite force exerted from the cutting insert.

In a first aspect, the present invention aims to eliminate the above drawbacks of reaming tools already known (by commercialization) and to provide an improved tool of this type. It is therefore a primary object of the present invention to provide, as a reaming tool, a reaming tool which can be manufactured such that the removable cutting insert of the reaming tool has two or more cutting edges. An additional object is a reaming tool, for the purpose of maximizing the user's working profit, the reaming cutting insert of the reaming tool has a minimum volume to provide a reaming tool with a minimum material cost in relation to the number of cutting edges available. It is. In addition, as a reaming tool, with respect to the possible extraction of the tool from the reaming hole, an intact intact cutting insert of the reaming tool is intended for the final purpose of facilitating the extraction and reducing the wasted time associated with possible machine failure. It is also an object of the present invention to provide a reaming tool that remains reliably in the installation position on the seat of the tool head.

According to the invention, at least the main object is achieved by the features described in the characterizing part of claim 1. Further preferred embodiments of the reaming tool according to the invention are described in the dependent claims 2 to 7.

In an additional aspect, the present invention also aims to provide a tool head and a reaming insert which ensures a good function of the assembly tool by improved properties. The unique features of the tool head and the individual cutting inserts are described in the dependent claims 8 and 15, respectively.

Terms

In the following text, a number of surfaces and blades of the cutting insert having the shape of a prismatic body and the sheet on which the cutting insert is installed will be described. In order to distinguish these surfaces and blades for the purpose of providing clarity of concept, the surfaces and blades differ from the following depending on whether they are related to the geometry of the cutting body and the sheet or to the function of the surface / blade in connection with chip removal. It is named. Thus, the concept of "restricted surface" is used in connection with the shape of the cutting insert being depicted, while the concept of "chip surface and clearance surface" is used to further clarify the function of the surface, respectively. Similarly, "blade" is used in connection with the insert shape, but if the blade is used for chip removal or surface wiping, the concepts of "cutting edge" and "second blade" or "wiper blade" are respectively Used. If a blade has only the purpose of defining two confinement surfaces with each other and is not used for machining purposes, the blade will be named "boundary edge or border". In addition, the active surface of the individual sheets of the tool head is generally named "support surface" while the surface of the cutting insert pressed against the support surface is called "contact surface". In addition, the concepts of "invertible" and "indexable" are used respectively. By the cutting insert according to the invention being "inverted" it is meant that the chip surface already exposed outward is directed inward with respect to the support surface for the purpose of exposing the other mirrored chip surface outwardly. By the cutting insert being "indexed" it is meant that the cutting insert is dismounted and rotated 180 ° about its central axis and then installed on the seat. The purpose of the present invention as well as the indexing of cutting inserts is to, in a conventional manner, change to a cutting edge which is not used when the cutting edge already in use wears out, and each individual cutting edge must have the same spatial position in the tool head.

As a courtesy, it is to be noted that the cutting insert is typically made from cemented carbide or other hard wear resistant material, while the tool head is made of softer material, in particular steel. The material of the workpiece to be machined is mainly metallic, although other materials may be present, such as composites.

1 is a perspective view of a reaming tool according to the present invention in an assembled state.
2 is an exploded perspective view of the same tool.
3 is a side view of the tool shown in the longitudinal section during reaming of the hole in the workpiece in the form of a tube blank.
4 is an exploded side view of the head included in the tool, in which a cutting insert is provided.
5 is a front view of the head in the same state.
6 is a perspective view of a tool head provided with a cutting insert.
7 is an exploded perspective view showing the cutting insert separated from the sheet and the sheet included in the tool head together with the clamping member for the cutting insert.
8 is an enlarged aerial view of an individual cutting insert according to the present invention.
9 is a perspective view of the same cutting insert.
10 is a side view of the cutting insert.
11 is a view seen from above (or below) the cutting insert.
12 shows the end of a cutting insert.
FIG. 13 is a longitudinal enlarged cross-sectional view taken along the line VIII-VIII in FIG. 11.
14 is an enlarged exploded view of a longitudinal section showing a part of the cutting insert and the sheet separated from each other.
15 is a longitudinal enlarged cross-sectional view of an obtuse corner of a cutting insert in an installed state.

The reaming tool T shown in Figs. 1 to 3 comprises three main parts: a drive rod 1, a head 2, and a plurality of cutting inserts 3 detachably installed on the head. The illustrated embodiment of the reaming tool also includes a lock member in the form of a nut 4, a forerunner 5, and a bushing 6 acting between the forerunner and the drive rod. During operation, the reaming tool can generally be rotated and the workpiece can be conveyed in the longitudinal direction or in the longitudinal direction as the workpiece is rotated to provide the required relative motion between the workpiece and the reaming tool. In the example shown, the one mentioned last is preferred, ie while the workpiece 7 shown in the form of a tube blank is rotated in the direction of the arrow R, the tool is conveyed in the longitudinal direction, i.e. in the direction of the arrow F. do. When the concepts of "front" and "rear" are used in the following description, respectively, they are for the conveying direction F along the longitudinal direction. Thus, in FIGS. 1 and 2, the tool is shown from behind. If the tool is shown from the front according to FIG. 5, in this case, the tube blank 7 rotates counterclockwise about the central axis C, wherein the drive rod 1 and the other parts 2, 4, 5, 6) are concentric.

The purpose of this machining method, which is known to those skilled in the art as "full boring", is to ream the hole 8 of the workpiece or tube blank 7 so that a cylindrical surface having good dimensional accuracy and high surface smoothness ( 9) to provide. Initially, the tube blank 7 has an inner diameter ID1 which can be of any size smaller than the desired final inner diameter ID2 of the machined cylindrical surface 9. Internal surface finishing is not important. In the first step, for example, a drawbar 11 in the form of a tube having a diameter smaller than ID1 is allowed to pass through the hole 8 such that the drive rod 1 of the assembled tool T is for example a threaded joint. It can be applied to the rear projecting end via. Next, while the tube blank 7 is rotated, the drawbar and the tool are pulled back through the hole 8. In doing so, the cutting insert 3 removes the chips which are discharged via the discharge channel 12 backward from the tube blank, more specifically at the envelope surface of the head 2. In order to facilitate the discharge and at the same time ensure that the chip does not damage the formed cylindrical surface 9, the fluid (eg water) is flushed backwards through the tube blank.

When the tool is assembled, the forerunner 5 and the bushing 6 are first fitted to the drive rod 1 and then the head 2 is fitted. In order to fix the head 2 against rotation, the head comprises an opening having a polygonal (square) cross-sectional shape in which a driver of a similar polygonal shape of the drive rod is engaged. Finally, the head 2 is fixed by the lock nut 4. A forerunner 5 comprising a plurality of elastic fingers which are resiliently tensioned about the inside of the tube blank 7 and which, in rotation, follow the tube blank for centering and guiding the distal head. With the bushing 6 serving as a bearing, it can freely rotate with respect to the drawbar 1.

Reference is now made to FIGS. 4 to 7, which show how the head or base body 2 comprises the front and rear end faces 13, 14 and the cylindrical envelope face 15, the cylindrical envelope face being the center. Concentric with the axis C, it is converted to a flat front end face 13 via the conical surface 16. On the envelope surface 15, a plurality of (17 in this example) sheets 17 for cutting inserts are formed. In this case, the sheet 17 is partially open at the envelope surface 15 and partly at the conical surface 16. Each sheet includes three support surfaces to transmit radial, tangential and axial cutting forces acting on the cutting insert during chip removal. Of these support surfaces, the radial support surfaces are indicated by reference numeral 18 and the tangential support surfaces are indicated by reference numeral 19. In this case, the stepped portion of the inclined surface 22 in which the third support surface in the form of the axial support surface 20 extends perpendicular to the tangential support surface 19 and at an obtuse angle with respect to the radial support surface 18 ( 21). Although all support surfaces are generally shown in the form of flat and single surfaces, certain surfaces, such as tangential support surfaces 19, are intended to prevent overlapping of the cutting inserts and to ensure accurate positioning of the cutting inserts in the sheet. It can be divided into a plurality of partial surfaces by shallow drainage channels. And a countersunk clearance surface for the blade portion of the cutting insert is formed in the transition between the surfaces 19 and 22. In the traditional manner, the sheet has a tipped-in position (indicated by the angle α in FIG. 5) in the head, for the purpose of providing the necessary clearance for the cutting inserts to be installed.

At the transition between the radial support surface 18 and the inclined surface 22, for cooperative operation with the male threaded portion 24 of the screw 25, which serves as a clamping member for the purpose of securing the cutting insert to the seat 17. A hole 23 having a female screw portion (not shown) is opened. The screw 25 comprising the conical head 26 is advantageously spring biased in order to press the cutting insert not only against the surfaces 18, 22 but also against the surface 19 when tightened. At the boundary line 27 located at a distance from the tangential support surface 19 and extending approximately parallel to the tangential support surface, the radial support surface 18 is switched to one of the channels 12 described above.

In the preferred embodiment shown, a stop lug 28 located along the radial support surface 18 is also included, the function of which stop lug will be described later.

Reference is now made to FIGS. 8 to 13, which show in detail the design of the reaming insert according to the invention.

In general, the cutting insert extends between six faces or constraining surfaces, ie two opposite parallel surfaces 29 (hereinafter referred to as “chip surfaces”), and two chip surfaces 29. It has the shape of a polyhedron with four surfaces 30 serving as clearance surfaces. These clearance surfaces 30 are identical, but the suffixes "a", "b", "c" and "d" have been assigned to the clearance surfaces in FIGS. 8 and 9 so as to be distinguished from one another. In a similar manner, two identical chip surfaces 29 are distinguished by the suffixes "a" and "b", respectively. In other figures, the suffix is omitted. In FIG. 8, SP1 represents a plane of symmetry which is located parallel to and in between the chip surfaces 29a, 29b. Where the second symmetry plane SP2 extends perpendicular to the plane of symmetry SP1 and these planes of symmetry intersect at right angles to each other, the first central axis C1 is present.

According to the invention, the reaming inserts according to the invention have a rhombic base shape, so that each arbitrary cross section parallel to the chip surfaces 29a, 29b is a rhombus shape.

In the figure, the chip and clearance surface is shown as a flat surface, but does not exclude that the topographical shape of the surface inside the outer boundary line can deviate from the purely flat shape. In particular, the chip surface 29 may be formed of various non-flat partial surfaces with the purpose of guiding and / or breaking the chip to be removed.

The clearance surfaces 30 meet each other in pairs at an obtuse angle β (see FIGS. 10 and 13) at two opposite corners 31x, 31y. Thus, the clearance surfaces 30a, 30b meet at the corner 31x, while the clearance surfaces 30c, 30d meet at the corner 31y. For simple geometrical reasons, the surfaces 30a, 30d and 30b, 30c meet each other in an acute angle at the corners 32x, 32y, respectively. In addition, a second central axis across the center of the two rhombic chip surfaces 29a, 29b is indicated by reference C2 (see FIGS. 8 and 9). Between each individual chip surface and the connecting clearance surface, two cutting edges are formed which can be used in the tool shown, ie cutting edges 33- between the chip surface 29a and the clearance surfaces 30a, 30b. 1 and 33-2 are formed, and cutting edges 33-3 and 33-4 are formed between the chip surface 29b and the clearance surfaces 30b and 30d. Via a short second or wiper blade 34, individual effective cutting edges, for example cutting edges 33a, are switched to the latter, which cleans the surface produced during machining. By the chamfer surface 35 formed between the chip surface 29a and the clearance surface 30b, the wiper blade 34 is provided (in order to avoid unnecessarily too much reference numerals in FIGS. 8 and 9, the other three Reference numerals are omitted for the chamfer surface and the wiper blade).

In this example, β is 135 ° and γ corresponds to 45 °. These angles can vary upwards and downwards. However, β should be 110 degrees or more and 160 degrees or less, and it is appropriate to exist in the range of 120-150 degrees.

In the example shown, when the clamping member consists of a screw 25, the through hole 36 extends through the cutting insert, more specifically between the obtuse corners 31x and 31y. At the opposite end, this hole 36 comprises a ring shaped conical countersink 37, which countersink has no index position with respect to the center axis C2 (indexing is the cutting insert). Is done by rotating 180 ° about the central axis C2) to accommodate the screw head 26.

It should be noted that all clearance surfaces 30 extend perpendicular to the plane of symmetry SP1 and thereby also perpendicular to the chip surface 29.

In each of the four clearance surfaces 30, a cavity 38 comprising four confinement surfaces is broadly formed on top, and one of these confinement surfaces, namely the surface 39, has a stepped portion in the sheet 17. 21 to form an axial contact surface for pressing against the axial support surface 20. The other limiting surface of the cavity consists of two sides 40 and a clearance surface 41, which advantageously (but not necessarily) has an angle σ of 90 ° with the axial contact surface 39. Form. In FIG. 13, it is appropriate for the axial contact surface 39 of the cavity of any clearance surface (eg, 30c) to form a right angle ε with the adjacent clearance surface 30d adjacent to the same corner 31y. Thus, when the last mentioned clearance surface 30d is kept pressed against the radial support surface 18 of the seat 17, the tightening screw 25 is axially as well as radial to the tool head. Since a tightening force component is applied to the cutting insert, the axial contact surface 39 is brought into surface contact with the axial support surface 20.

The width of the individual cavity 38, calculated as the distance between the sides 40, is slightly larger than the width of the step 21 (calculated between its sides). In the example shown, the width of the cavity 38 is, on the one hand, much smaller than the width of the clearance surface 30 (calculated between the chip surfaces 29), which means that the cavity is clearance on all sides in this case. It means surrounded by the surface. In this regard, it should be noted that the cavity may be characterized by a groove extending along the entire width of the clearance surface and opening at the opposing chip surface.

Reference is now made to FIGS. 14 and 15, in which the axial contact surface 39 of the cavity 38 is in contact with the axial support surface 20 of the step 21 in the installed state of the cutting insert. You can see that. However, the upper side 42 of the step portion 21 does not contact the clearance surface 41 of the cavity 38. The clearance surface 30 of the cutting insert is also not in contact with the inclined surface 22 of the sheet. Indeed, the play or gap G can reach a number of hundredths or tens of millimeters. For example, G may be 0.02 to 0.25 mm, preferably 0.05 to 0.10 mm.

It should also be noted that the cross-sectional shape of the stop lug 28 is without exception smaller than the corresponding (triangle) cross-sectional shape of the cavity 38. In that way, the two confinement surfaces 43, 44 of the stop lug 28 are usually cleaned from the two surfaces 39, 41 of the cavity. Furthermore, the gap G between the pair of surfaces can here be up to 0.25 mm.

When the cutting insert remains pressed against the seat by the cutting force during operation (a clearance surface 30 against the radial support surface 18, an inactive chip surface 29 against the tangential support surface 19, and The axial contact surface 39 with respect to the axial support surface 20, the shoulder surface 43 of the stop lug and the axial contact surface 39 of the cooperating cavity potentially form a fixing function, which function Never interferes with the normal fastening of the cutting insert in the seat. However, if a failure occurs, the tool head needs to be retracted out of the hole to be machined, so that the cutting insert moves the cutting insert away mainly from the axial support surface 20 and also from the tangential support surface 19. And the fastening function is quickly exerted, keeping the cutting insert very close to its original fastening position. This is done by pressing the axial contact surface 39 of the associated cavity directly against the shoulder surface 43 of the stop lug 28. In practice, this means that the opposite axial force acting on the cutting insert (if the screw can continue to press the cutting insert against the radial support surface 18) is absorbed more quickly by the stop lug than the tightening screw 25. . In order to ensure fast activation of the fastening function and to avoid screw breakage, the gap G should in all cases be within the above-mentioned range of 0.25 mm or less, suitably 0.15 mm or less, most preferably 0.05 to 0.10 mm.

The main advantage of the reaming inserts according to the invention is that four cutting edges are available due to the lozenge basic shape of the reaming inserts, despite the minimally reduced cutting insert volume compared to the already known reaming inserts. In other words, the cutting insert ensures good profit for the user. And the possible extraction of the tool out of the machined tool is much easier, and the waste of time for dealing with possible failures requiring such extraction is reduced. Due to the fact that the volume of the cutting insert is minimized, the reaming tool according to the invention may be configured for very small hole diameters.

Possible Modifications of the Invention

타입의 커플링이 사용될 수 있다.The present invention is not limited only to the embodiment described above and shown in the drawings. Thus, the cutting insert can be secured to the accessory sheet by a clamping member other than a screw, such as a clamp, wedge or tightening finger. A potential fastening function, although desirable on its own, is not required, and it is not noticed that each of the cooperatively acting axial contact surface and the axial support surface is formed in the cavity of the cutting insert and in the step along the slope. Thus, especially if the obtuse angle between the inclined surface and the radial support surface is limited, it is possible to use a suitable inclined surface as the axial support surface such that the inclined surface extends more steeply with respect to the radial support surface than in the illustrated example. The angle between the chip surface and the individual clearance surface need not be perpendicular. It is also possible within the scope of the present invention to change the obtuse angle (and acute angle, respectively) of the rhombus within quite wide limits. However, when the axial support surface is disposed on the stepped portion along the inclined surface, the obtuse angle should be 160 ° or less and 110 ° or more. In addition, the cutting insert and the sheet can be formed such that the radial cutting force is transmitted not only by the contact between the surfaces 41, 42 but also by a part of the clearance surface (left part of the stop lug 28 of FIG. 15). . The tool can also be manufactured so that it can be pushed instead of being pulled through the reaming hole. In addition, the mechanical coupling between the tool and the drawbar or connecting rod may have a shape other than that shown. For example, COROMANT CAPTO

Type of coupling can be used.

Claims (17)

A reaming tool comprising a drive rod (1) and a head (2) having a basic shape of rotational symmetry and equipped with at least one removable cutting insert (3),
The head comprises front and rear end faces 13, 14, an envelope face 15 concentric with the central axis C, and a sheet 17 formed wider at the envelope face, the sheet being Three support surfaces, one of which is a radial support surface 18 and the other being a tangential support surface 19,
The cutting insert has the shape of a mirror-symmetric polygon comprising six confinement surfaces 29, 30, of which two mutually parallel opposing surfaces are equidistantly separated from the central symmetry plane SP1 and the chip surface ( 29) and this chip surface is connected to a limiting surface 30 which serves as a clearance surface via the same cutting edge 33 available alternately,
In the reaming tool in which the cutting insert is held fixed to the seat by the clamping member 25,
The cutting inserts 3 have a rhombic cross-sectional shape at the plane of symmetry SP1 and comprise four clearance surfaces 30, which meet each other in pairs at an obtuse angle β at two opposite corners 31. And along each individual chip surface 29, together with the chip surface, two cutting edges 33 which are alternately available by indexing of the cutting inserts are formed,
Reaming tool, characterized in that the sheet (17) comprises, in addition to the radial support surface (18) and the tangential support surface (19), an inclined surface (22) at an obtuse angle with the radial support surface (18). The method of claim 1,
An axial support surface 20 is included in the stepped portion 21 formed along the inclined surface 22,
Reaming, characterized in that, on each of the clearance surfaces 30 of the cutting insert 3, a cavity having an axial contact surface 39 pressed against the axial support surface 20 of the stepped portion is widely formed. tool. The method of claim 2,
The axial support surface 20 of the sheet makes an angle of 70 to 110 ° with the radial support surface 18,
In the cavity 38, which is formed broadly upward in the first clearance surface 30 of the cutting insert, the neighboring agent in which the axial contact surface 39 is connected to the same obtuse corner 31 as the first contact surface. 2 Reaming tool, characterized by the same angle as the clearance surface. The method according to any one of claims 1 to 3,
The clamping member is a screw 25 consisting of a male threaded portion 24 and a head 26 and positioned in the through hole 36 between the obtuse corners 31 of the cutting insert, the male threaded portion 24 of the screw. The reaming tool characterized in that it is fastened to a female thread part included in a hole (23) opened in the transition part between the radial support surface (18) and the inclined surface (22) of the seat (17). The method of claim 4, wherein
The through hole 36 through the cutting insert 3 comprises a ring shaped countersink 37 at each of the two opposite ends for receiving the threaded head 26 irrespective of the index position of the cutting insert in the seat. Reaming tool, characterized in that. 6. The method according to any one of claims 1 to 5,
As well as an obtuse angle between the radial support surface 18 and the inclined surface 22 of the sheet, as well as an angle β between the two clearance surfaces 30 of the cutting inserts 3 which meet each other at an obtuse corner 31. Reaming tools, characterized in that 110 ° or more and 160 ° or less. The method according to any one of claims 1 to 6,
The individual clearance surface 30 of the cutting insert 3 is at right angles to the individual chip surface 29 and the radial support surface 18 and the tangential support surface 19 of the sheet are perpendicular to each other. Reaming tool. A reaming insert for a reaming tool according to any one of the preceding claims, wherein the reaming insert has the shape of a mirror-symmetric polygon comprising six confinement surfaces (29, 30), two of which are parallel to each other. The opposing surface serves as the chip surface 29 while being equidistantly separated from the central symmetry plane SP1, which serves as a clearance surface via the alternately available cutting edge 33. ) In the reaming insert, which is connected to
It has a rhombic cross-sectional shape at the plane of symmetry SP1 and comprises four clearance surfaces 30, which meet each other in pairs at an obtuse angle β at two opposing corners 31 and meet each individual chip surface. Together with the chip surface, thereby forming two cutting edges 33 which are alternately available by indexing the cutting insert. The method of claim 8,
Reaming inserts, characterized in that on each of said clearance surfaces (30) a cavity (38) comprising an axial contact surface (39) is formed broadly upward. The method of claim 9,
In the cavity 38, which is broadly formed at the first clearance surface 30, each of the individual axial contact surfaces 39, as a first contact surface, is connected to the same obtuse corner 31 as a neighboring second clearance. Reaming inserts characterized by being perpendicular to the surface 30. 11. The method according to any one of claims 8 to 10,
The obtuse angle β is reaming insert, characterized in that more than 110 ° 160 °. The method according to any one of claims 8 to 11,
A reaming insert, characterized in that it comprises a through hole 36 extending between the obtuse corners 31. The method of claim 12,
The reaming insert, characterized in that the hole (36) is located solely in the plane of symmetry (SP1). The method according to claim 12 or 13,
A reaming insert, characterized in that a countersink (37) for the screw head is formed at each opposite end of the hole (36). A rotationally symmetrical head for a reaming tool according to any of the preceding claims, comprising a front and rear end face (13, 14), an envelope face (15) concentric with the central axis (C), and cutting A seat 17 for receiving the insert, which is wider at the top of the envelope face 15 and comprises three support faces, one of which is a radial support face 18 and In the rotationally symmetrical head for the reaming tool, the other being the tangential support surface 19,
Rotational symmetry for reaming tools, characterized in that the sheet comprises, in addition to the radial support surface 18 and the tangential support surface 19, an inclined surface 22 which is obtuse with the radial support surface 18. head. The method of claim 15,
A rotationally symmetrical head for a reaming tool, characterized in that a third support surface in the form of an axial support surface 20 is included in the stepped portion 21 formed along the inclined surface 22. 17. The method of claim 16,
A symmetrical head for reaming tool, characterized in that the axial support surface (20) of the step (21) is perpendicular to the radial support surface (18) and at an acute angle with the inclined surface (22).

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